Axial flow fan



P. A. swam. 2,457,325

mm. mm: mm

Film! Bay 15, 1943 1 4 Sheets-Sheet l I N VEN TOR. PHIL/P A s/aeu v BY v Dec. 28,1948. m ,v 2,451,325

AXIAL rnow mm I Filed Way 15, 1943 v 4 Sheets-Sheet 2 INVENTOR. PHIL/P A. SIDEU;

Dec. 28, 1943.

P. SIDELL AXIAL FLOW FAN 4 Sheets-Sheet 3 Filed Bay 15, 1943 IN VEN TOR. PHILIP A, .SIDELL I Dec. 28, 194 8. L I 2,457,325

Filed lay 15. 1943 4 Sheets-Sheet. 4.

' AXIAL FLOW mu FIG; 8

- IN VEN TOR.

PHIL/P A. S/DEZL Patented 28, 1948 FLQW FAN Application May 15, 1943, Serial No. 487,090

6 Claims. (oi. 170-173) The present invention relates to fluid impelling devices and more in articular to axial flow fans of multi-part construction in which the parts maybe readily and easily fabricated and assembled to provide the complete fan assemblies.

Among the objects of the present invention is to provide an axial flow fan which is rigid and rugged in its construction and in which the blades are mounted upon and secured to a centrally disposed blade supporting element such that the blades are in planes angularly disposed in respect to the plane of rotation of the supporting element.

A further object of the present invention is to provide a novel axial flow fan which is simple in construction, but which meets all operating conditions, and which attains a high degree of efiiciency in its operation.

More particularly the present invention is grounded upon a desire to provide a suitable axial flow fan assembly in which the connection between the blades and the central supporting element is such as to secure increased strength and which more effectively resists the various stresses to which such blades are usually subjected.

As one of the principal objects the present invention contemplates a connection between the blades and the central supporting element which is formed by virtue of the provision of notches at the inner ends of the blades extending in the direction of the major axis thereof and which allows the marginal portions of the blade forming the slot to straddle the central supporting element and to be secured in such relation. More particularly the notched or slotted formation of the blades permits the blades to be disposed in their desired pitch relation to the plane of rotation of the fan, and provides for contacting relation of the marginal edges of the slot with the opposed faces of the central supporting element. The provision oi the slotted formation for the blades with their line contact with the central supporting element lends itself admirably to the use of various means for connecting the blades to the central supporting element, which effectively resists centrifugal and radial stresses as well as bending moments at the root of the blades, and all of which stresses arecarriedby the attachment or fastening means in shear, thus greatly increasing the desirable structural characteristics of such an assembly as distinguished from the structures of theprior art.

Another object of the present invention is to provide a novel axial flow fan assembly in which the connection between the blades and the central supporting element involves the use of notched blades straddling the said element, and which provides substantially extended line engagemen't between the same to greatly increase the strength of the resulting fan structure.

A further object of the present invention is to provide a novel connection between the blades and the central supporting element of an' axial flow fan, in which the blades are formed with notches whereby the blades are adapted to straddle the said element and the marginal portions defining the slot or notch for the blades, are adapted to be offset in various angular relation to the blade itself to secure any desired line contact between the blades and element, thus assuring a rigid attachment of the blades to said element.

A still further object of the present invention is to provide a novel connection between theblades and the central supporting element of an axial fiow fan involving the use of notches at the ends of the blades which can be varied as to their depth and formation to provide a connection between the blades and element which will eii'ectively resist in shear, both at thetop and bottom thereof, the bending moment to which the blades are subjected, and which holds the blades rigid against rotation or vibration about the axis thereof.

Still another object of the present invention is to provide a novel form of connection between the blades and a central supporting element of an axial flow fan involving the use of slots at the inner ends of the blades which may be of any desired formation to readily permit the manufacturer of such blades to provide for any variation in pitch of the said blades in the fan assembly.

Another object within the purview of the present invention is to provide a novel connection between the blades and a central supporting element of an axial flow fan involving the provision of slots at the ends of the blades, and in which the marginal portions defining the slots may be chest in respect to the blade in any desired mannor to facilitate the connection of the blades to the element without the use of special fittings, but which lends itself admirably to the use of such fastening means as angular fittings, bolts, screws or welding. V.

A further desideratum of the present invention is to provide a simplified construction in which the marginal portions of the blades defining the slots may take any formation desired to two directions.

A still further object of the present invention is to provide an axial flow fan of multi-part construction'in which the connection between the blades and a central supporting element is such as to minimize radial fluid flow and turbulence created thereby, thus securing maximum efliciency of operation of the said fan assembly.

' More particularly the invention contemplates a connection such that portions of the fan blades in connected and assembled relation with a supportingelement act as barriers preventing radial fluid flow in the assembly.

As an additional object, the present invention contemplates an axial flow fan of multi-part construction in which the said parts are connected to one another in such a manner as to facilitate protection of the fan after it is assembled against corrosion or rust, either by painting, spraying or plating.

Other objects, features, capabilities and advantages are comprehended by the invention, as will later appear and as are inherently possessed thereby.

Referring now to the drawings Figure 1 is a view in elevation of a fan assembly made in' accordance with the present invention and having parts thereof broken away to more clearly disclose certain detailed construction thereof;

Figure 1A is an end view of a blade for the assembly of Figure l of the drawings;

Figure 1B is a view in side elevation of a blade for the assembly of Figure 1 of the drawings;

Figure 2 is a view partly in section and partly in side elevation of the fan assembly shown in Figure 1 and taken in the planes represented by line 2.-2 of that figure;

Figure 3 is a view in elevation of a modified form of fan assembly made in accordance with the present invention and having parts broken away to disclose certain of the structure more in detail;

Figure 4 is'a view partly in section and partly in side elevation of the fan assembly shown in Figure 3 and taken in the planes represented by line 44 of that figure;

Figure 5 is a fragmentary view in elevation of still another form of construction for a fan made in accordance with the present invention;

Figure 6 is an enlarged fragmentary view in elevation of a single blade and its associated support of the fan assembly shown in Figure 5 of in side elevation of the fan assembly shown in Figure 8 and taken in the plane represented by the line 8-4 of that figure.

Referring now more in detail to the drawings, one embodiment selected to illustrate the present invention is shown in Figures 1 and 2 as comprising an axial flow fan of multipart construction, comprising a plurality of blades 2 of similar construction mounted upon and secured to a central supporting element 4 which, in the present illustration, is formed from a member of substantially disc-like construction. Secured to the central portion of the member 4 is a bearing 6 whereby the fan impeller is adapted to be mounted upon and keyed or otherwise secured to a shaft 8, which may be the driving shaft of a motor or other source of power adapted to rotate the impeller about the axis of said shaft.

away to disclose certain parts of thestructure more in detail; and

Figure 9-is a view partly in section and partly The present invention is primarily concerned with a suitable attachment for the blades to the central supporting member 4 which lends rigidity to the resulting assembly and which facilitates the ready manufacture and fabrication as well as the assembly of the component parts of the impeller at low cost. Such a connection involves the provision of slots ill at the inner ends of these blades, whereby the marginal Portions forming the slots are disposed in straddling relation to the periphery or circumference of the supporting element 4 andwhich provides for the connection of the blades to said element by means of welding or the like. In the illustrative example of the invention as shown in Figures 1 and 2, the slot I ll diverges outwardly toward the inner end of the blades and is of a suflicient depth to provide marginal portions l2 and 14 which will provide a suitable connection between the blades and the central supporting element 4. In accordance with this disclosure the marginal portions l2 and M are bent in offset relation to the general plane of the blade to dispose their marginal edges defining the slot ill in parallel planes, so that such marginal edges have substantially line contact with the outer radially extending faces I6 and I8 of the element 4. The formation of the slots is such that the marginal edges thereof are in substantial contact with the faces l6 and I8 both radially and circumferentially of the element 4 and in opposed relation to the longitudinal axis of the blades to assure rigidity of the assembled fan structure. It is to be noted, also, that the blades are so disposed that their working faces are angularly arranged with respect to the plane of rotation of the fan to provide the desired pitch therefor.

By virtue of the particular offset relation of the marginal portions l2 and H with respect to. the general plane of the blades substantial support is provided for the blades to assure rigidity in the connection thereof to the supporting element 4,

and which connections are adapted to resist in blades to the element 4, the blades can be readily fabricated to make'possible any variation in the pitch of the fan blades with respect to the element 4 by the simple procedure of varying the particular formation for these slots. As clearly shown in the drawings, the blades are curved to approximate an aerofoil section from the outer end thereof to adjacent the inner end of the slot Ill so as to secure the advantages in efficiency which result from such formation in an impeller blade of this type.

In Figures 3 and 4 is disclosed a modified axial flow fan assembly made in accordance with the present invention, the same being of multi-part construction involving a plurality of blades Zll and a central supporting element 22, which latter element has the bearing 240 secured thereto, whereby the impeller may be suitably mounted upon and secured to a shaft,'such as shaft of the first described embodiment.

In this modified structure, the central supporting element 22 comprises two dished disclike sections at and 26 formed with the outer complementary annular flanges such as 28, which are secured or fastened together as by means of spot-welding or the like, and provide a cylindrical-like hub as illustrated in the drawings. The connection between the blades 28 and this hub 22 conforms essentially to the connection disclosed in Figures 1 and 2 of the drawings, except that the said blades at their inner ends are formed with a notch 30 defined by stepped marginal edges adapted to fit the peripheral formation of the hub 22 when disposed in operative straddling relation thereto. As in the first described illustration exemplifying the present invention, the marginal portions 32 and 3d defining the said notch 30 of these blades are bent in offset relation to the general plane of theblades and are provided as at 36 and 38, respectively, with flanges which are disposed in substantial parallel relation to the plane of the outside radial faces of the hub '22 when the said blades are disposed in operative relation to said hub. Y

The flanges 36 and 38 provide means whereby the blades may be fastened to the hub 2-2, as by rivets, welding or in any other desired manner.

As in the previously described embodiment of the invention, the particular connection for the blades in this assembly readily lends itself to all of the advantages which are characteristic of the present invention. In addition the blades as shown are formed to simulate an aerofoil section to secure the advantages of such formation in a device of the type herein illustrated.

In Figures 5, 6 and 7 is disclosed a further alternative form of construction for an axial fiow fan possessing the desirable characteristics of g fly wheel M. The blades M of this embodiment are of similar construction and are of a type intended 'for heavy duty. The connection be tween the blades ill and the ring-like supporting element 52 conforms generally to the connections between the blades and supporting elements of the previously described assemblies, and involves the provision of a notch adjacent the inner end of the blade to provide the marginal portions 52 and 5t adapted to straddle the ring-like member 62.

In this particular embodiment marginal portion 54 is bent into offset relation to the main part of the blade $0 so as to have line contact with one surface of the ring-like member d2, much on the order of the line contact existing between the blades and supporting elements of the previously described structures. The marginal portion 52, however, is shown as being extended laterally to form a tab 56, which is offset in curved relation to the marginal portion 52 as at 58 whereby the outer marginal edge 60 of the said tab 56 is in contacting relation with the face of the ring-like member 42. To complete the connection between the blades and the ring-like member 42 the portion 54 may be secured in position as by welding or the like, and the tab 58 may be secured as by means of welding along the marginal edge to only, or if desired additional welding may be efiected along the marginal edge of portion 52.

As will be noted from Figure 7 of the drawings, that portion of the blade between the notch 50 and the edge of the tab 56 abuts the periphery of the flanged drum or fly wheel M whereby air is prevented from being drawn up behind the blade, thus increasing the efliciency of a blade of this type. I

The particular provision of a tab as illustrated in Figures 5, 6 and 7 provides for additional rigidity for the blade and permits of the formation of various side and bottom pockets which might, under many conditions, be desirable to increase the efficiency of the fan by preventing the radial porting element or to one another. While this embodiment is merely illustrative of the tab formation for the blades in an assembly as contemplated by the present invention, nevertheless, if desired, oppositely opposed tabs could be The fundamental inventive concept as hereinbefore disclosed, lends itself admirably to modifled constructions such as shown in Figures 8 and 9 of the drawings, to provide interlocking engagement between the fan blades and the central blade supporting element. In this further illustrative embodiment of the invention the assembly includes the central blade supporting element 62 formed with a central bearing 5%, whereby the impeller may be suitably mounted upon and se-' cured to a shaft, such as shaft 8 of the first described embodiment. The central supporting element '62 of this construction is further characterized as being provided with an enlarged rim forming part 66, providing the inner annular shoulders 68 and it disposed on opposite sides of the main part it of the said supporting element.

Mountedupon the periphery of the central supporting element B2 is a plurality of fan blades it constructed much on the order of the fan blades of the previously disclosed structures, and which are further formed with theslots l6 adjacent their inner ends. The slot of each of these blades is formed by the tabs 78 and all to provide an enlarged opening 82 and a diverging slot portion 8d. These tabs it and 80' are provided with the lugs 8t and 88 extending into the'slot 16, and

.which are adapted in one position of the blade to interlockingly engage the shoulders 88 and it.

The presentassemblyis particularly characterized by virtue of the formation of the slot 16, which is of such a construction that the tabs 18 and 80 may be moved into straddling relation with respect to the supporting member 62 when the blade is in one angular position with respect to said supporting element, but which provides for interlocking engagement of the lugs 86 and 88 with the shoulders 68 and when the blade is twisted into its final operative position with respect to the supporting element 62. As in previousiy described assemblies, the tabs 18 and 80 have contacting relation with the main part 12 of the supporting element, as at 90, and the said blades may be secured in such operative relation to the supporting element by means of a weld joint at the point of contact therewith. It is, of course, understood that the tabs I8 and 80 may be formed to provide the additional features of construction which have been more particularly disclosed and described in the structures of Fi ures 1 to 7. r

While Figures 8 and 9 are illustrative of a certain interlocking relation between the blades and the supporting element. it is to be understood that all of the advantages of this type of structure may be secured by the provision of slots or grooves formed on the supporting element 62, providing shoulders adapted to be engaged by lugs of the blades to interlock the same together. The interlocking relation of the blades and supporting element has the advantage of increasing the rigidlty of the fan assembly as a whole, and may be a desirable structure where the assembly is subjected to particularly heavy duty during its operation.

While I have herein described and upon the drawings shown illustrative embodiments of the invention, it is to be understood that the invention is not limited thereto but may comprehend other constructions, arrangements of parts, de-

tails and features without departing from thespirit of the invention.

I claim: V 1. An axial flow fan comprising a'central blade supporting element having adjacent its periphery.

opposed side surfaces disposed in substantially parallel planes, a plurality of blades formed from metal plates connected to said surfaces and having their fluid impelling surfaces aneularly disposed with respect to the plane of rotation of said element, the connection between each of said blades and said element being characterized in that a slot is provided in the base of each blade in such manner as to provide anchorage sections on both sides of said slots, said anchorage sections being mounted in straddling relation with respect to the periphery of said element and having their slot defining edges disposed in abutment with the opposed surfaces of said element, said anchorage sections extending in opposed relation peripherally whereby to dispose said edges in substantially parallel planes to provide 8 for substantial line contact thereof with the surfaces of said element when said blades are mounted angularly on said element and means for securing said anchorage section to said element.

2. An axial flow fan according to claim 1, in

.which the anchorage sections are bent out of the general plane of said fluid impelling surfaces from adjacent the end of said slots.

3. An axial flow fan according to claim 1, in which the slots increase in width toward the open end thereof and said anchorage sections are bent out of the general plane of said fluid impelling surfaces from adjacent the end of said slots.

4. An axial flow fan according to claim 1, in which one of said anchorage sections is extended peripherally of said blade supporting element to provide a tab having an outer edge disposed substantially in the plane of the edge of said anchorage section defining said slot and adapted to have substantially line contact with one of the surfaces of said element.

5. An axial fiow fan according to claim 1, in which one of said anchorage sections is extended peripherally of said blade supporting element to provide a tab of curved formation having its outer edge disposed substantially in the plane of the edge of said anchorage section defining said slot Number and adapted to have substantially line contact with one of the surfaces of said element.

6. An axial flow fan according to claim 1, in which said supporting element and blades are formed with shoulders interengageable when said blades are disposed in angular relation to said supporting element.

PHILIP A. SIDELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain Sept. 27, 1938 Great Britain Oct. 24, 1939 Number 

